Background: Surgical resection for cancer is becoming more minimally invasive with smaller incisions and less patient morbidity. However, this process switches the burden to the surgeon to remove all the disease with suboptimal visualization. This project proposes to develop a technique to employ preoperative injection of ultra- sound contrast enhancement stationary microbubbles and micro/[nano]shells to enable intraoperative detection of tumors even in cases with small skin incisions to allow surgeons to better identify and completely resect tumors and decease patient morbidity. Aims: To determine the optimal dose and lifetime of stationary microbubbles in a rabbit model as an ultrasound contrast agent in order to localize small breast tumors for surgical resection. To study the localization ability of a novel gas filled silica micro/[nano]shells compared to microbubbles as an ultrasound contrast agent and localization method for occult breast cancers using a rabbit model. Conclusion: Surgical resection of small early cancers remains important in local control and prevention of metastases, techniques to improve its efficacy in visualizing and removing tumors completely can have a major impact on breast and other cancer treatment. It is critical to improve the localization and visualization of non- palpable cancers due to the inability to detect these tumors during surgery. This fact is particularly important in this era in which tiny cancers are detected by imaging and more advanced techniques are needed for localizing tumors. This project may be able to decrease positive margins, local recurrence and possible cure of early stage cancers.